feature fails to update automatically

I have a model with sophisticated parameter control. (Very sorry for no uploading due to company confidence!) A Combined Projection feature always fails to update correctly when a key expression value is changed.

I make a study and find that it's due to "Projection Direction 2":

• After I change the expression value, I open the Combined Projection feature for editing and find that it is "Projection Direction 2" that does not update automatically (Fig.1). Then I change the project direction to "Along Vector" and then back to "Normal to Curve Plane". Now the "Projection Direction 2" points to the updated direction (Fig.2) and then the Combined Projection feature would update correctly.

I wonder what can be done to fix it. Very sorry for so frequent post. Thank you!

Fig.1 Before manual operation        Fig.2 After manual operation